APPENDIX B

CALIFORNIA INTERIM CERTIFICATION PROCEDURES FOR 2004 AND

SUBSEQUENT MODEL HYBRID-ELECTRIC VEHICLES, IN THE URBAN BUS

AND HEAVY-DUTY VEHICLE CLASSES

Adopted: [insert date of adoption]
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A. Applicability

The certification procedures in this document are applicable to 2004 and

subsequent model year heavy-duty hybrid-electric vehicles and urban transit

buses (HEBs).

General procedures and requirements necessary to certify a heavy-duty engine

for sale in California are set forth in “California Exhaust Emission Standards and

Test Procedures for 1985 and Subsequent Model Heavy-Duty Diesel Engines

and Vehicles” (hereinafter “HDD TPs”), as incorporated in title 13, CCR, section

1956.8(b), and “California Exhaust Emission Standards and Test Procedures for

2004 and Subsequent Model Heavy-Duty Otto-Cycle Engines,” (hereinafter

“HDO TPs”), as incorporated in title 13, CCR, section 1956.8(d), for testing and

compliance of heavy-duty diesel and Otto-cycle engines with exhaust emission

standards.

The interim certification procedures are optional for the 2004 through 2006 model

years. The Executive Officer shall review test results and in-use data gathered

from the 2004 through 2006 model years and make recommendations to the

Board in 2006 for modifying certification procedures for 2007 and subsequent

model year HEBs and heavy-duty hybrid-electric vehicles.

B. Definitions

These certification procedures incorporate by reference the definitions and

abbreviations set forth in 40 CFR §86.001-2 (October 22, 1996) and §86.004-2

(January 18, 2001), the definitions and abbreviations set forth in the HDD TPs,

the definitions set forth in the HDO TPs, and the definitions set forth in title 13,

CCR sections 1956.1 through 1956.8, unless otherwise amended below.

1. “Auxiliary power unit (APU)” means a device that converts consumable

fuel energy into mechanical or electrical energy. Examples of auxiliary power

units are internal combustion engines, turbines, and fuel cells.

2. “Baseline HEB engine” means the most representative heavy-duty

engine in a specific heavy-duty engine family certified by the Executive Officer

that will be used in a hybrid-electric drive system for a specific HEB family.

Certified emissions from the selected engine will be used in calculating an

emission factor to determine the appropriate emission reduction for a particular

hybrid-electric drive system.

3. “Baseline urban transit bus” means a representative,

non-hybrid-electric urban transit bus selected by the Executive Officer for chassis

dynamometer testing. Exhaust emissions from the selected urban transit bus, as

determined by the chassis dynamometer test procedure, will be used in
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conjunction with the certified emissions from the engine incorporated into the

baseline urban transit bus to calculate a baseline emission factor.

4. “Battery” means a device that stores chemical energy and releases

electrical energy.

5. “Battery rated Ampere-hour capacity” means the manufacturer-rated

capacity of a battery in Ampere-hours obtained from a battery discharged at the

manufacturer’s recommended discharge rate (C/1 – C/6) such that a specified

minimum cut-off terminal voltage is reached.

6. “Battery State of Charge (SOC)” means the quantity of electric energy

remaining in the battery relative to the maximum rated Ampere hour (Ah)

capacity of the battery expressed in percent.

7. “Capacitor” means a device that stores energy electrostatically and

releases electrical energy.

8. “Capacitor SOC” means the actual measured energy content of a

capacitor and expressed as a percentage of the capacitor’s maximum rated

voltage squared (V2).

9. “CCR” means California Code of Regulations.

10. “CFR” means Code of Federal Regulations.

11. “Charge-depleting HEB” means an HEB that is designed to be

recharged off-board under normal conditions. Under conditions of continuous

operation, the RESS of a charge-depleting HEB ultimately fully discharges and

impairs vehicle operation when no off-board charging is performed and the

consumable fuel is regularly replenished.

12. “Charge-sustaining HEB” means an HEB that derives all of its energy

from on-board fuel under normal usage. Under conditions of continuous

operation, the RESS of a charge-sustaining HEB does not fully discharge and

impair vehicle operation when no off-board charging is performed and the

consumable fuel is regularly replenished.

13. “Electric drive components” means the electric motor, system

controller, generator, and energy storage system (batteries, capacitors, and

flywheels).

14. “Electromechanical flywheel” means a device that stores rotational

kinetic energy and releases that kinetic energy to an electric motor-generator

system, thereby producing electrical energy.
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15. “Electromechanical flywheel SOC” means a percentage of the

flywheel’s maximum-rated revolutions per minute squared (rpm2), which is based

on the actual measured energy content of an electromechanical flywheel.

16. “Emission factor” means the number calculated from exhaust emissions

chassis dynamometer test results and engine dynamometer test results for a

HEB or conventional urban transit bus. The number, expressed in units of bhphr/mi, is used to calculate an emission factor ratio.

17. “Emission Factor Ratio” means the number resulting from dividing the

emission factor for a HEB by the emission factor for a baseline urban transit bus,

and reflects the emission reduction capability of a hybrid-electric drive system.

18. “Hybrid-electric drive system” means the propulsion system comprised

of the APU and the corresponding electric drive components connected with that

APU.

19. “Hybrid-electric urban transit bus (HEB)” means an urban bus

equipped with at least two sources of energy stored on board; this energy is

converted to motive power using an electric drive motor and an APU. The

electric drive motor must be used partially or fully to drive the vehicle’s wheels.

20. “HEB Family” means the basic classification unit of a manufacturer’s

product line used for the purpose of test fleet selection, based on gross vehicle

weight (either 24,000 lbs to 44,000 lbs, or greater than 44,000 lbs). A family may

include any engine that certifies to the same standard as the HEB test vehicle.

21. “Net Energy Change (NEC)” means the net change in energy level of a

RESS expressed in Joules (watt-seconds).

22. “Propulsion energy” means energy that is derived from the vehicle’s

consumable fuel and/or RESS to drive the wheels. If an energy source is

supplying energy only to vehicle accessories (e.g., a 12-volt battery on a

conventional vehicle), it is not acting as a source of propulsion energy.

23. “Propulsion system” means a system that, when started, provides

propulsion for the vehicle in an amount proportional to what the driver

commands.

24. “Regenerative braking” means deceleration of the bus caused by

operating an electric motor-generator system. This act returns energy to the

vehicle propulsion system and provides charge to the RESS or to operate

on-board accessories.

25. “Rechargeable Energy Storage System (RESS)” means a component,

or system of components, that stores energy and for which the supply of energy
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is rechargeable by an electric motor-generator system, an off-vehicle electric

energy source, or both. Examples of RESS for HEBs include batteries,

capacitors, and electromechanical flywheels.

26. “SOC” See “Battery SOC”.

27. “SOC delta” means delta ampere-hours measured during a test.

28. “SOC final” means SOC at the end of a test run (Ah, V2, or rpm2).

29. “SOC initial” means SOC at the beginning of a test run (Ah, V2, or rpm2).

30. “Total Fuel Energy” means the total energy content of the fuel, in British

Thermal Units (Btu) or kWh, consumed during a test as determined by carbon

balance or other standard method and calculated based on the lower heating

value of the fuel.

C. Heavy-duty Hybrid-Electric Drive System Certification Requirements

Compliance with the heavy-duty hybrid-electric vehicle standards requires the

development of an emission factor ratio for a heavy-duty hybrid-electric drive

system with a certified baseline engine and comparison of the corresponding

emissions with the applicable (e.g., urban bus or heavy-duty diesel or Otto-cycle

engine) exhaust emission standards for a given engine by model year.

For model years 2004 through 2006, no more than two parties (i.e. the

engine/turbine/fuel cell manufacturer and the hybrid-electric drive manufacturer)

shall be granted an individual Executive Order identifying the emission standard

achieved by the engine/turbine/fuel cell and the hybrid-electric drive system. For

2007 and subsequent model years, only one Executive Order shall be granted

identifying the emission standard achieved by the hybrid-electric drive system.

1. One Party Responsibility. Where one party is responsible for

emissions, an Executive Order shall be granted identifying the emission standard

achieved by the HEB.

1.1 Certification Standards. All 2004 and subsequent model year

HEBs shall, by model year, meet the exhaust emission standards or optional

emission standards set forth in title 13, CCR, section 1956.1. The exhaust

emissions for the hybrid-electric drive system of the HEB shall be determined in

accordance with section D of this document. The certification standard for the

hybrid-electric drive system shall be determined in accordance with section E of

this document.

2. Two Party Responsibility. Where two parties are responsible for

emissions, two Executive Orders shall be granted. One Executive Order shall be
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granted to the engine/turbine/fuel cell manufacturer identifying the emission

standard achieved and one Executive Order shall be granted to a second party

identifying the emission standard of the hybrid-electric drive system.

2.1 Certification Standards. For model years 2004 through 2006, the

heavy-duty engine, turbine, or fuel cell used as a motive source in a HEB shall,

by model year and size, meet the exhaust emission standards or optional

emission standards set forth in title 13, CCR, section 1956, 1956.1, 1956.7, or

1956.8. All 2004 and subsequent model year hybrid-electric drive systems shall,

by model year, meet the exhaust emission standards or optional emission

standards set forth in title 13, CCR, section 1956.1. The exhaust emissions for a

hybrid-electric drive system shall be determined in accordance with section D of

this document. The certification standard for the hybrid-electric drive system

shall be determined in accordance with section E of this document.

3. 25 Percent Reduction Claim. For the 2004 through 2006 model

years, hybrid-electric drive system manufacturers may claim a 25 percent

reduction from the NOx certification standard of the engine or turbine

incorporated as part of the hybrid-electric drive system in lieu of following the test

procedures set forth in sections E and F. During that period, the Executive

Officer may request the manufacturer to perform chassis testing of a HEB

selecting this option in accordance with the test procedures in sections D and E.

If testing data indicate a reduction of exhaust emissions of less than 25 percent,

the HEB family shall receive that smaller reduction.

4. Useful Life. For the 2004 through 2006 model years, the useful life

of the hybrid-electric drive system shall be 5 years or 150,000 miles, whichever

comes first. After that time, the useful life of the hybrid-electric drive system shall

meet the useful life requirements for urban transit buses as set forth in title 13,

CCR, section 2112(20), as last amended October 24, 2002.

5. Emissions Warranty. For the 2004 and subsequent model years,

the hybrid-electric drive system shall, by model year, meet the warranty

requirements listed in title 13, CCR, sections 2035 and 2036, as last amended

December 26, 1990 and May 15, 1999, respectively.

6. Durability and Emission Testing. An HEB family with less than

50 HEBs sold for the 2004 through 2006 model years shall be exempt from

durability-data vehicle and emission-data vehicle testing. An HEB family in

California with 50 or more HEBs sold, and any 2007 and subsequent model year

HEB families shall meet the durability-data vehicle and emission-data vehicle

testing as required in title 13, CCR, section 2111 et seq, as last amended

December 28, 2000.

7. Labeling Requirements. The hybrid-electric drive system shall

meet labeling requirements as set forth in title 13, CCR, section 1965, as
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amended by the HDD TPs and the HDO TPs. In addition to the information

required by those labeling requirements, the hybrid-electric drive system

manufacturer shall also include the following information on the hybrid-electric

drive system label:

7.1 An unconditional statement of compliance with the appropriate

model year California regulations; for example:

“This vehicle (engine or hybrid-electric drive system, as applicable)

conforms to California regulations applicable to [insert MY date]

model year new, (for 2004 and subsequent model years,

specify heavy-duty Otto-cycle engines, heavy-duty diesel engines,

or urban transit bus engine, as applicable).”

For federally certified vehicles certified for sale in California, the

statement must include the phrase “conforms to U.S. EPA regulations and is

certified for sale in California.”

For 2004 and later model year hybrid-electric drive systems to be

used in urban buses that incorporate an on-road heavy-duty diesel engine and

are certified to the optional reduced-emission standards, the label shall contain

the following statement in lieu of the above:

“This hybrid-electric drive system conforms to California

regulations applicable to [insert MY date] model year new urban

bus engines and is certified to a NOx plus NMHC optional reducedemission standard of [insert appropriate number] g/bhp-hr (for

optional reduced-emission standards specify between 0.3 and 1.8,

inclusive, at 0.3 g/bhp-hr increments), and a particulate matter

standard of [insert appropriate number] g/bhp-hr (specify 0.03

g/bhp-hr, 0.02 g/bhp-hr, or 0.01 g/bhp-hr).”

7.2 For 2004 and subsequent model year hybrid-electric drive systems

used in urban transit buses, if the manufacturer is assigned an alternative useful

life period by the Executive Officer, the label shall contain the statement:

“This engine has been certified to meet California standards for a

useful life period of [specify] years or [specify] miles of operation,

whichever occurs first. This hybrid-electric drive system’s actual life

may vary depending on its service application.”

The manufacturer may alter this statement only to express the

assigned alternate useful life in terms other than years or miles (e.g., hours or

miles only).
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7.3 For 2004 and subsequent model year hybrid-electric drive systems

used in urban transit buses, the label shall contain the statement:

“This hybrid-electric drive system has a primary intended service

application as an urban transit bus engine. It is certified to the

emission standards applicable to an urban transit bus.”

8. Engine Service Manuals and Equipment Maintenance Signals.

The hybrid-electric drive system manufacturer shall meet service manual and

maintenance signal requirements as set forth in 40 CFR §86.004-38 (October 21,

1997) and §86.007-38 (January 18, 2001) as amended by the HDD TPs and the

HDO TPs.

9. Rebuild Provisions and Recordkeeping Requirement. The

heavy-duty engine rebuilding practices set forth in 40 CFR §86.004-40 (October

21, 1997) as amended in the HDD TPs and HDO TPs shall also apply to the

hybrid-electric drive system.

10. Information Requirements. In addition to the requirements set

forth in the HDD TPs and the HDO TPs, the certification application shall include

the following:

10.1 Identification and description of the hybrid-electric drive system

covered by the application.

10.2 Identification of the heavy-duty vehicle weight category to which the

vehicle is certifying: light heavy-duty, medium heavy-duty, heavy-heavy duty, or

urban transit bus; and the curb weight and gross vehicle weight rating of the

vehicle.

10.3 Identification and description of the propulsion system for the

vehicle.

10.4 Identification and description of the climate control system used on

the vehicle.

10.5 Projected number of heavy-duty hybrid-electric vehicles produced

and delivered for sale in California.

10.6 All information necessary for the proper and safe operation of the

vehicle, including information on the safe handling of the battery system,

emergency procedures to follow in the event of battery leakage, or other

malfunctions that may affect the safety of the vehicle operator or laboratory

personnel.
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10.7 Method for determining battery state-of-charge and any other

relevant information as determined by the Executive Officer.

11. Safety Procedures. For 2004 and subsequent model years, a

manufacturer shall conform to the requirements specified in title 13, CCR,

division 2, chapter 6.5, articles 1, 3, and 8, inclusive.

D. Hybrid-Electric Drive System Test Procedures

These test procedures incorporate by reference SAE J2711, “Recommended

Practice for Measuring Fuel Economy and Emissions of Hybrid-Electric and

Conventional Heavy-Duty Vehicles” (April 2002), as modified in these test

procedures to apply to HEBs sold in California. For the 2004 through 2006

model years, heavy-duty hybrid-electric vehicles may follow these or equivalent

procedures provided the manufacturer obtains prior written approval from the

Executive Officer (EO).

The test procedure for determining compliance with standards applicable to the

turbine or fuel cell used as the motive power in a hybrid-electric bus shall be

determined by the Executive Officer on a case-by-case basis.

1. Chassis Dynamometer Test Preparations

1.1 Test Site. The ambient temperature levels encountered by the test

vehicle shall be no less than 20 °C (68 °F) and no greater than 30 °C (86 °F).

Ambient temperatures shall be recorded at the beginning and end of the test

period. Adequate test site capabilities for safe venting and cooling of batteries,

protection from exposure to high voltage, and any other necessary precaution

shall be provided during testing. A fixed-speed fan shall direct cooling air to the

vehicle to maintain the engine operating temperature as specified by the

manufacturer during testing, and shall be operated only when the vehicle is in

operation. Fans for brake cooling may be utilized during testing.

1.2 Pre-Test Data Collection. Vehicle demographics shall be

recorded prior to testing including the vehicle identification number, gross vehicle

weight (from vehicle data plate), curb weight (from vehicle data plate or by

weighing), engine manufacturer, model year and type, engine serial number,

engine displacement and number of cylinders, engine rated power and speed,

tire size, transmission type, number of speeds, presence or absence of retarder,

exhaust gas aftertreatment type, and rear axle ratio. Pre-test data shall also

include details of the type, power, and speed of the electric motor(s); and type

and capacity of the RESS.

1.3 Fuel Specifications. The test fuel shall meet the certification

specifications set forth in the HDD TPs and HDO TPs.
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1.4 Vehicle Preparation. Vehicle preparation and preconditioning

shall be conducted in accordance with 40 CFR §86.1231-90 (April 11, 1989) and

40 CFR §86.1232-90 (April 11, 1989).

1.4.1 Prior to testing, the vehicle shall be stabilized to a manufacturerdetermined distance or to 4,000 miles.

1.4.2 Vehicles shall be tested at curb weight plus driver weight and one

half seated passenger load using a weight of 150 lbs per passenger.

1.4.3 Manufacturer’s recommended tires shall be used. Tire pressures

shall be set at the beginning of the test at the pressure used to establish the

dynamometer road-load coefficients and shall not exceed levels necessary for

safe operation. Tires shall be conditioned as recommended by the vehicle

manufacturer and shall be the same size as would be used in service.

1.4.4 The vehicle lubricants normally specified by the manufacturer shall

be used.

1.4.5 The vehicle shall be driven with appropriate accelerator pedal

movement to achieve the time-versus-speed relationship prescribed by the

driving cycle. If test vehicles are equipped with manual transmission, the

transmission shall be shifted in accordance with procedures that are

representative of shift patterns that may reasonably be expected to be followed

by vehicles in use.

1.4.6 If the vehicle has a regenerative braking system, the vehicle shall

be tested on the dynamometer with the identical control strategy as used in

service. Vehicles equipped with an antilock braking system or traction control

system may require modifications (i.e. defeat) to those systems during

dynamometer testing to achieve normal operation of the regenerative braking

system.

1.4.7 If necessary, vehicles with air suspension may be aired up from an

external source prior to testing. After the vehicle has reached sufficient air

pressure to achieve proper suspension leveling and service brake operation,

external air shall be disconnected from the vehicle and shall not be reconnected

during emissions testing or between testing events during the key-off period.

1.4.8 Off-vehicle charging shall be allowed only for the battery

conditioning of charge-sustaining HEVs.

1.5 Chassis Dynamometer Specifications. The chassis

dynamometer shall be capable of mimicking the transient inertial load,

aerodynamic drag and rolling resistance associated with normal operations of

heavy-duty vehicles. The transient inertial load shall be simulated using
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appropriately sized flywheels or electronically controlled power absorbers. The

driver shall be provided a visual display of the desired and actual vehicle speed

to allow the driver to operate the vehicle on the prescribed cycle.

1.5.1. Coastdown analysis. The drag and rolling resistance shall be

established as a function of vehicle speed as referenced in 40 CFR §1229-85

(October 6, 2000) or another appropriate method approved by the Executive

Officer. The vehicle weight for the on-road coastdown shall be the same as the

anticipated vehicle testing weight as simulated on the dynamometer. Vehicles

equipped with regenerative braking systems that are activated at least in part

when the brake pedal is not depressed shall have their regenerative braking

systems disabled during the deceleration portion of coastdown testing, preferably

through temporary software changes in the vehicle’s control system

1.6 Test Instrumentation. Equipment referenced in 40 CFR

§86.1301-90 (April 11, 1989) to 40 CFR §86.1326-90 (April 11, 1989) (including

exhaust emissions sampling and analytical systems) shall be required for

emissions measurements. All instrumentation shall be NIST-traceable (National

Institute of Standards and Technology). The following instruments shall be

required for as-needed usage: a DC wideband Ampere-hour meter with an

integration period of less than 0.05 seconds if an integration technique is used;

an instrument to measure a capacitor’s voltage; an instrument to measure an

electromechanical flywheel’s rotational speed; an AC Watt-hour meter to

measure AC Recharge Energy; and a voltmeter and ammeter. Tunnel flow

volume shall be set at the minimum level possible for vehicles such that a carbon

balance for fuel efficiency and a hydrocarbon balance for tunnel integrity can be

performed accurately and the lowest possible detection limits can be determined.

Emission levels that are determined to be below detection limit shall be cited as

less than the detection limit value.

2. Chassis Dynamometer Test Procedure

2.1 Vehicle Propulsion System Starting and Restarting. The

vehicle’s propulsion system shall be started according to the manufacturer’s

recommended starting procedures in the owner’s manual. Only equipment

necessary to the primary propulsion of the vehicle during normal service shall be

operated.

2.2 Driving cycles. Chassis testing shall include two separate test

cycles as follows: one cold start and three hot start tests using the Orange

County bus cycle (Appendix C); and one cold start and three hot start tests using

the Urban Dynamometer Driving Schedule (UDDS) (40 CFR §86 Appendix I(d))

(April 29, 1998).
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2.2.1 During the interim certification period, the Executive Officer may

request data from one cold start and three hot starts using the Central Business

District (CBD) cycle which will not be used for certification.

2.2.2 The applicant may request a substitution of one test cycle with one

representative of specific transit fleet operation for approval of the Executive

Officer.

2.2.3 The test vehicle shall be operated through at least one preliminary

run of the desired test cycles to familiarize the driver with vehicle operation and

verify function of laboratory instrumentation.

2.2.4 A cycle length of approximately 30 minutes shall be used for all

chassis tests. For driving cycles less than 30 minutes in duration, repetitions of

the cycle shall be run back-to-back for a total cycle length of approximately

30 minutes. Chassis tests shall also consist of a normalized condition prior to the

test, including either a 12-hour cold soak or a warm-up followed by a 20- to

30-minute key-off period.

2.2.5 If at any point during the test vehicle propulsion is not possible or

the driver is warned by the vehicle to discontinue driving because the RESS

energy supply is too low, the test shall be considered invalid.

2.3 Cold and Hot Emission Tests

2.3.1 Cold start test cycles shall include all emission data from the

moment the vehicle is started, including the actual start event. The vehicle shall

be cold soaked for a minimum of 12 hours to ensure that all components are at

ambient temperature. The vehicle shall remain in the key-off position for

30 minutes until testing begins. A separate vehicle or other equipment (e.g.

electric heaters) as necessary shall be utilized to bring the dynamometer to

operating temperature. The vehicle shall be started and idled for one minute,

after which time the 30-minute test cycle shall commence. Emission

measurements shall be taken from one minute before the vehicle is started

through test cycle completion. At the end of the test cycle the vehicle shall be

returned to the key-off condition.

2.3.2 Hot test cycles shall include all emission data from the moment the

vehicle is started, excluding the actual start event. The vehicle shall be started

and warmed to operating temperature utilizing the same test cycle that will be

used for emission characterization. Multiple back-to-back hot test events must

include a 20- to 30- minute key-off condition in between each test event. Once

the vehicle is at operating temperature the vehicle shall be turned off and will

remain in the key-off position for approximately 20 to 30 minutes. The vehicle

shall be restarted and idled for one minute, at which time the 30-minute test cycle
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shall begin and emission measurements will be taken. At the end of the test

cycle the vehicle shall be returned to the key-off condition.

2.4 Intra-test Pauses. Between two test events, the vehicle shall

remain with the key switch in the key-off position for 20 to 30 minutes, with the

engine enclosure closed and the brake pedal not depressed.

2.5 Test Termination. The test shall be terminated at the conclusion

of the test run. If necessary, a one-minute idle may be added at the end of the

test cycle before termination for collection of emissions remaining in the sampling

train.

2.6 Data Recording.

2.6.1 The emissions from the vehicle exhaust shall be ducted to a

full-scale dilution tunnel where the gaseous emissions of hydrocarbons, carbon

monoxide, oxides of nitrogen (both nitric oxide and nitrogen dioxide) and carbon

dioxide shall be measured on a continual basis at a frequency of 5 Hz or greater.

An integrated bag sample of the dilution tunnel may be collected and analyzed

for carbon monoxide and carbon dioxide levels, and these may be compared to

the continuous measurements for carbon monoxide and carbon dioxide as a

quality assurance check. Modal results must be within five percent of bag

sample results for modal results to be used. Alternatively, the measured values

for carbon monoxide and carbon dioxide may be obtained from the integrated

bag sample. Particulate matter shall be measured gravimetrically using

fluorocarbon-coated glass fiber filters by weighing the filters before and after

testing. Filters shall be conditioned to temperature and humidity conditions as

specified in 40 CFR §86.1312-88 (September 5, 1997).

2.6.2 For each constituent, a background sample using the same

sampling train as used during the emission testing shall be measured before and

after the emission test, and the background correction shall be performed as

specified by 40 CFR §86.1343-88 (September 5, 1997). For a compressed

natural gas-fueled vehicle, and in cases where non-methane hydrocarbons are a

species of interest, the integrated methane and non-methane content of

hydrocarbons shall be measured, using gas chromatography analysis of

integrated bag samples for each run. If necessary, the tunnel inlet may be

filtered for PM with a HEPA filter to aid in lowering the detection limits.

2.6.3 Fuel consumed shall be determined by carbon balance from the

analytical instruments, and the number of dynamometer roll revolutions shall be

used to determine the distance traveled during the driving cycles.

2.6.4 SOC of the vehicle shall be measured continuously (at a rate of

1Hz or greater) and recorded throughout the entire test. Recorded data shall

then be time integrated against the emission measurement data at the beginning
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and end of the test to coincide with the emission measurement portion of the

chassis test. Provided the SOC is measured, time sequenced and integrated in

accordance with the procedures in this document, only the beginning and ending

SOC values are necessary in the final test report. Both Ah and system voltage

shall be recorded during the test, as outlined in the method for determining NEC.

3. Final Report.

3.1 Exhaust Emissions and FE. The exhaust emissions and fuel

economy of the vehicle shall be reported in grams per mile and miles per diesel

equivalent gallon, respectively. Total fuel energy shall be reported in British

Thermal Units (Btu).

3.1.1 Calculations for exhaust emissions are referenced in 40 CFR

§86.1342-90 (September 5, 1997) with the following revision to paragraph (a):

AWM = (1/7)(YC/DC) + (6/7)(YH/DH)

Where:

AWM = Weighted mass emission level in grams per vehicle mile

YC = Mass emissions from the cold start test in grams

YH = Averaged mass emissions from the hot start tests in grams

DC = Measured driving distance from the cold start test in miles

DH = Averaged measured driving distance from the hot start tests

in miles

3.2 SOC Difference. The state of charge difference of the RESS shall

be measured during the test and reported along with the RESS NEC.

3.3 Net Energy Change (NEC). NEC calculations for batteries,

capacitors, and electromechanical flywheels are listed below.

3.3.1 Batteries. Either of two equations may be used to calculate the

NEC for batteries:

(1) NEC = [SOCfinal – SOCinitial] * Vsystem * K1

where
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SOC = Battery SOC at the beginning and end of the test run, in

Ampere-hours (Ah). If the SOCfinal and SOCinitial values are

in amp-seconds, the conversion factor is not used.

Vsystem = Battery’s DC nominal system voltage as specified by the

manufacturer, in volts (V)

K1 = Conversion factor = 3600 (seconds/hour; not used if SOCfinal

and SOCinitial values are in seconds)

or,

(2) NEC = SOCdelta * Vsystem * K1

where

SOCdelta = Delta Ampere-hours during a test

Vsystem = Battery’s DC nominal system voltage as specified by the

manufacturer, in volts (V)

K1 = Conversion factor = 3600 (seconds/hour; not used if SOCfinal

and SOCinitial values are in seconds)

3.3.2 Capacitors. The following equation calculates NEC for capacitors:

NEC = (C/2) * [SOCfinal – SOCinitial]

where

SOC = The capacitor SOC at the beginning and end of the test run,

in (V)

2

C = Rated capacitance of the capacitor as specified by the

manufacturer, in Farads (F)

3.3.3 Electromechanical Flywheels. The following equation shall be

used to calculate NEC for electromechanical flywheels:

NEC = (1/2) * I * [SOCfinal – SOCinitial] * K2

where

SOC = Flywheel state-of-charge at the beginning and end of the test

run, in (rpm)

2
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I = Rated moment of inertia of the flywheel system, in

kilogram-meter2 (kg-m2)

K2= Conversion factor = 4π

2

/3600 (rad2/sec2/rpm2)

3.4 NEC Variance Determination.

3.4.1 Total Fuel Energy. Total fuel energy is the energy value of the

fuel consumed by the internal combustion engine, turbine, or fuel cell during the

test and shall be calculated using the following equation:

Total Fuel Energy = NHVfuel * mfuel

where

NHVfuel = Net heating value (per consumable fuel analysis as specified

by ASTM) in Joules per kilogram (J/kg)

Mfuel = Total mass of fuel consumed over test, in kilograms (kg)

3.4.2 Total Cycle Energy. The total cycle energy shall be reported in

watt-seconds or converted to kWh.

Total Cycle Energy = Total Fuel Energy – NEC

3.4.3 Determination Procedure. To determine if a test run has an

acceptable NEC, divide NEC by total cycle energy. If the absolute value of the

calculation yields a number less than or equal to 2%, as shown in the equation

below, the NEC variance is within tolerance levels.

(NEC/total cycle energy) * 100% < 2%

Test runs with NEC variance greater than +/- 2% shall be considered invalid.

3.5 Final Test Report. The final test report shall include all measured

parameters, including vehicle configuration, vehicle statistics, test cycles,

measured parameters and calculated test results.

4. Charge-Depleting Hybrid-Electric Vehicles.

Modifications to this procedure for measuring fuel economy and emissions of

charge-depleting heavy-duty hybrid-electric vehicles may be made upon approval

of the Executive Officer.
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5. Conventional Drivetrain Urban Transit Buses.

Modifications to this hybrid-electric drive system procedure for measuring fuel

economy and emissions of conventional drivetrain urban transit buses may be

made upon approval of the Executive Officer.

E. Certification by Emission Factor Ratio Application

The applicant shall provide both engine and vehicle test results when using the

following procedure. Engine test results shall be obtained from an engine

manufacturer who has complied with the HDD TPs, HDO TPs, or alternative

procedures approved by the Executive Officer. Vehicle test results shall be

obtained from the party certifying the hybrid-electric drive system in accordance

with the procedures set forth in Section D of this document. An emission factor

shall be calculated from the two results to determine the emissions reduction

achieved by the hybrid-electric drive system.

1. Emission Factor. An emissions factor shall be calculated by

following equation:

EF = Vehicle NOx (g/mi) 

Engine NOx (g/bhp-hr)

where

EF = emission factor of the vehicle in bhp-hr/mi

Vehicle NOx = weighted mass emissions level of NOx determined from

chassis dynamometer testing in g/mi

Engine NOx = weighted mass emissions level of NOx determined from

engine dynamometer testing in g/bhp-hr

Emission factors shall be calculated for HEBs and for baseline urban transit

buses. The baseline urban transit bus shall be selected by the Executive Officer

and tested by the Air Resources Board. The resulting data will be available for

use by manufacturers applying for certification.

2. Emission Factor Ratio. An emission factor ratio shall be

calculated by the following equation:

EFR = EFhybrid

EFbaseline

where

EFR = emission factor ratio
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EFhybrid = emission factor calculated for a hybrid-electric urban transit

bus

EFbaseline = emission factor calculated for a baseline urban transit bus

3. Application of Emission Factor Ratio for Hybrid-Electric Bus

Certification. The NOx certification value for a hybrid-electric bus shall be

calculated by applying the following equation:

HEBcert = EFR * Engine NOx

where

HEBcert = hybrid-electric bus NOx certification value in g/bhp-hr

EFR = emission factor ratio

Engine NOx = weighted mass emissions level of NOx determined from

engine dynamometer testing in g/bhp-hr